The U.S. Secret Service is investigating a profanity-laced and violent message directed at vanquished presidential candidate Hillary Clinton that was written on the back of a minivan and spotted traveling this week on a busy interstate northwest of the Twin Cities.

The words on the van were photographed early Wednesday afternoon by another person heading west on Interstate 94 near the Hwy. 101 exit in Rogers. The handwritten message read: “If Hillary wins I hope to god some one shoots her in her [expletive] head.” A second sentence of three words included two more vulgarities.

“It is a matter that the Secret Service is investigating,” Louis Stephens, the agency’s special agent in charge based in Minneapolis, said Thursday afternoon. “Making threats against people protected by the Secret Service is a violation of federal law.”

The van is owned by a 47-year-old man from Zimmerman, a city roughly 18 miles north of where the vehicle was seen on I-94. Court records show the man has convictions in Minnesota for violating orders for protection and fifth-degree assault.

Telephone calls by the Star Tribune to the man Thursday afternoon were not answered.

Rogers Police Chief Jeff Beahen said his department is trying but so far has been unable to reach the van’s owner.

He said law enforcement will have to decide whether the words are “a direct threat against Hillary Clinton, or are they putting their anger out on the back of a window.”

At a minimum, Beahen said, the message could be considered disorderly conduct given that “there are a couple of different words on the back that are unacceptable.” The words might possibly draw a more serious terroristic threat charge, the chief added.

The person who took several photos of the back of the van said a middle-aged man wearing sunglasses was behind the wheel. He then contacted police in Rogers and the Secret Service, and shared the photos with them.

“I initially could only make out that it had something to do with Hillary, so I pulled closer to be able to read what it said,” said the man, who asked that his name not be published out of concern for his safety. “I immediately took pictures of the vehicle so I could use it as evidence, and capture the license plate.”

Chief Beahen said this type of message “is very upsetting to the traveling public. There’s freedom of speech, but keep it to the verbiage protected by the First Amendment.”